Wiper arrangement for motor vehicles, especially for car windscreens

ABSTRACT

In a wiper system for vehicles, in particular for automobile windshields, including a first wiper arm, a primary drive motor ( 12 ) associated with the wiper arm for generating a defined wiping motion of the first wiper arm, at least one second wiper arm, and a secondary drive motor ( 13 ) associated with the second wiper arm for generating a defined wiping motion of the second wiper arm, the secondary drive motor ( 13 ) being controlled as a function of the position of the primary drive motor ( 12 ), a motor position code element ( 23 ) is provided, which is coupled to the primary drive motor ( 12 ) and is provided with control codes ( 24 ) that are directly representative of the associated position of the secondary drive motor ( 13 ). For scanning the control codes ( 24 ) of the motor position code element ( 23 ), a scanner unit ( 25 ) is used, which via a signal connection ( 22 ) is connected to a controller ( 27 ) of the secondary drive motor ( 13 ).

The invention relates to a wiper system for vehicles, in particular forautomobile windshields.

In such dual-drive-motor wiper systems, each wiper arm is driven by itsown drive motor. For performing the desired wiping operation on thewindshield, the wiper arms must sweep over the field to be wiped with aprecisely defined speed profile. This profile can be achieved, forinstance via an electronically controlled drive motor, by means ofspecifying desired variables. Alternatively, this speed profile can alsobe attained by a nonreversing, that is, a revolving cylinder drivemotor, with a suitable wiper arm connection, for instance via a rodlinkage. In order to attain a precisely defined relationship at alltimes between the wiping motions or wiper arm positions of the two wiperarms, regardless of external loads that actually act upon the wiperarms, coupling of the two drive motors is necessary. To that end, thewiper arm moved by a primary drive motor proceeds through its wiper pathin accordance with a planned desired wiping path course. The actualposition of the primary drive motor is sensed and transmitted to asecondary drive motor, which drives the second wiper arm. Theinformation about the position of the primary drive motor is processedin a microcontroller and taken into account in calculating the desiredposition of the secondary drive motor. The secondary drive motor is thuscontrolled as a function of the position of the primary drive motor.

A disadvantage of this known wiper system is the requisite precisecalculation of the position of the secondary drive motor as a functionof the position of the primary drive motor. This calculation requires amicrocontroller, which stands in the way of an especially economicalembodiment of a wiper system.

With this as the point of departure, it is the object of the inventionto design a wiper system of the generic type in question such that theposition of the secondary drive motor is controlled especiallyfunctionally reliably as a function of the primary drive motor, withoutrequiring an expensive drive motor controller.

SUMMARY OF INVENTION

The nucleus of the invention is considered to be that a motor positioncode element is provided which is coupled with the primary drive motorand has control codes that are directly representative of the associatedposition of the secondary drive motor. As a result of this design, anespecially economical wiper system is achieved, since calculation of theposition of the secondary drive motor as a function of the primary drivemotor to achieve a precisely defined relationship between the tworespective wiper arm positions is not done. Instead, the secondary drivemotor is supplied directly with control commands, which because of thephysical coupling between the code element and the primary drive motorhave the requisite exact association with the position of the primarymotor. An alternative storage of the applicable position of thesecondary drive motor in memory as a function of the primary drive motoris also dispensed with. Consequently, in this wiper system of theinvention a microcontroller is not necessary.

Other advantageous features are defined by the dependent claims.

The invention is described in further detail below in terms of apreferred exemplary embodiment in conjunction with the drawings. Shownare:

FIG. 1, a schematic front view of a dual-drive-motor wiper system; and

FIG. 2, a schematic view of a coupling according to the invention of thetwo drive motors in this wiper system.

A dual-drive-motor wiper system shown in FIG. 1 includes two wiper arms1, 2, which are intended for wiping an automobile windshield 3. Eachwiper arm 1, 2 has a wiper rod 4, 5, which on its respective free end 6,7 carries a wiper blade 8, 9 and which is pivotably connected by itsother end 10, 11 to a fastening arm 14, 15 that is connected to a drivemotor 12, 13. The wiper rod 5 can optionally also be mounted directly onthe driven shaft of the drive motor unit 13. The fastening arms 14, 15are pivotably connected to a driven shaft 16, 17 of the drive motors 12,13. The drive motor 12 shown on the left in FIG. 1 is the primary drivemotor of the wiper system and is embodied as a revolving cylinder motor,as also indicated by arrow 18. The drive motor 13 shown in the righthalf of FIG. 1 will hereinafter be called the secondary drive motor andis driven in reversing fashion, as indicated by the arrow 19.

For actuating the drive motors 12, 13 and thus also the wiper arms 1, 2,an actuating lever 20 in the interior of the vehicle is provided, whichis associated with the secondary drive motor 13 via a connecting line21. The two drive motors 12, 13 communicate with one another via asignal connection 22.

As seen in FIG. 2, an optical motor position code disk 23 is coupledwith the primary drive motor 12 shown schematically in the left half ofFIG. 2. This code disk is mounted on the driven shaft 16 of the primarydrive motor 12 and includes binary control codes 24, in the form ofpartial-circle strips disposed on concentric annular paths, and thesecodes are directly representative of the associated position of thesecondary drive motor 13. This means that for each position of theprimary drive motor 12, a corresponding desired position of thesecondary drive motor 13 is stored in memory; that is, the motorposition code disk 23 contains control codes for the desired wipingmotion of the wiper arm 2 associated with the secondary drive motor 13.

For scanning the control codes 24 contained on the motor position codedisk 23, a conventional optical scanner unit 25 with scanning diodes 26is provided. By means of the motor position code disk 23 and the scannerunit 25, a digital desired value signal for the position of thesecondary drive motor 13 is generated. This digital desired value signalis transmitted over the signal connection 22 to a controller 27associated with the secondary drive motor 13. The controller 27, at itsinput, includes a digital/analog converter 28. Downstream of thedigital/analog converter 28 is an analog controller 29, whose output isconnected to the input of a rectifier bridge 30. Angle signals of theposition of the secondary drive motor 13 are also transmitted to theanalog controller 29. These angle signals are sensed by a measuring unit31 associated with the driven shaft 17 of the secondary drive motor 13.The digital/analog converter 28 and the analog controller 29 serve toprocess the digital desired value signal and to providevoltage-controlled regulation of the position of the secondary drivemotor 13 as a function of the position of the primary drive motor 12.Optionally, the corresponding control voltage for the secondary drivemotor can have a voltage pilot control superimposed on it, whose valueis generated from a corresponding code in the code disk 23. Regulatingthe secondary drive motor 13 neither requires a memory component inwhich the desired position of the secondary drive motor 13 is stored,nor calculation of the position of the secondary drive motor 13separately from data pertaining to the position of the primary motor.

The relationship of the two drive motors 12, 13 to one another is thewell-known relationship of master to slave.

Alternatively to the embodiment described with the optical motorposition code disk 23, an embodiment with a magnetic motor position codedisk is also conceivable. In an especially inexpensive embodiment of thecontroller 27, only analog components are provided.

1. A wiper system for vehicles, comprising: a first wiper arm (1), aprimary drive motor (12) associated with the wiper arm, for generating adefined wiping motion of the first wiper arm (1), at least one secondwiper arm (2), and a secondary drive motor (13), associated with thesecond wiper arm, for generating a defined wiping motion of the secondwiper arm (2), the secondary drive motor (13) being controlled as afunction of the position of the primary drive motor (12), characterizedby a motor position code element (23), which is coupled to the primarydrive motor (12) and is provided with control codes (24) that aredirectly representative of the associated position of the secondarydrive motor (13); a scanner unit (25) for the control codes (20) of themotor position code element (23); and a signal connection (22) betweenthe scanner unit (25) and a controller (27) of the secondary drive motor(13).
 2. The wiper system of claim 1, wherein the primary drive motor(12) is embodied as a revolving cylinder engine.
 3. The wiper system ofclaim 1, wherein the secondary drive motor (13) is embodied as areversing motor.
 4. The wiper system of one of claim 1, wherein thesecondary drive motor (13) is provided with a voltage pilot control,wherein a value of the voltage pilot control can be generated by anadditional code in the code element (23).
 5. The wiper system of one ofclaim 1, wherein the motor position code element (23) is embodied as acode disk.
 6. The wiper system of claim 5, wherein the code disk (23) isembodied as an optical code disk.
 7. The wiper system of claim 6,wherein the scanner unit (25) includes scanning diodes (26).
 8. Thewiper system of claim 5, wherein the code disk (23) is embodied as amagnetic code disk.
 9. The wiper system of one of claim 1, wherein bymeans of the code element (23) and the scanner unit (25), a digitaldesired value signal for the secondary drive motor (13) can begenerated, which for processing and regulating the digital desired valuesignal and for its regulation has a digital/analog converter (28) and ananalog controller (29).
 10. A wiper system for vehicles, comprising: afirst wiper arm (1), a primary drive motor (12) associated with, thewiper arm, for generating a defined wiping motion of the first wiper arm(1), at least one second wiper arm (2), and a secondary drive motor(13), associated with the second wiper arm, for generating a definedwiping motion of the second wiper arm (2), the secondary drive motor(13) being controlled as a function of the position of the primary drivemotor (12), characterized by a motor position code element (23), whichis coupled to the primary drive motor (12) and is provided with controlcodes (24) that are directly representative of the associated positionof the secondary drive motor (13), so that for each position of theprimary drive motor (12), a corresponding desired position of thesecondary drive motor (13) is contained on the motor position codeelement (23): a scanner unit (25) for the control codes (20) of themotor position code element (23); and a signal connection (22) betweenthe scanner unit (25) and a controller (27) of the secondary drive motor(13).